This disclosure relates to a temperature detector for determining the physical profile of temperature rises to a predetermined temperature. It is capable of providing a physical profile of temperature rises spreading through an adjacent heated element.
This invention arose from tests requiring measurement of selected operational parameters within nuclear fuel bundles. It meets projected fuel bundle instrumentation requirements for development of peak temperature profiles along the length of a fuel bundle. This is desirable in the design, testing and use of the fuel bundle in order to provide a temperature profile at temperatures approaching that at which fuel rod meltdown would occur. Such measurements can be accomplished conventionally by the use of multiple thermocouples, but their costs and electrical connector requirements make such use prohibitive in actual practice.
The present device utilizes two or more elongated electrical conductors encased so as to be positionable immediately alongside fuel rods or other elongated elements. It includes a plurality of meltable metal segments spaced apart from one anther along one electrical conductor. The preselected melting point of these segments determines the operational temperature monitored by the device. Electrical insulators are mounted on the conductors for separably supporting molten material from the individual meltable segments in locations electrically bridging the conductors. The changes in resistance between the two conductors that results from such bridging can be monitored and measured from both ends of both conductors to provide a temperature profile indicating the spread of the preselected temperature in the device.